-Why vacuum packaging
-Types of home vacuum packaging systems
-Not a substitute for canning or dehydration
-Shelf life of vacuum packaged foods
-Vacuum Sealers and Bags
Why vacuum packaging?
Foods maintain their freshness and flavor 3-5 times longer than with
conventional storage methods, because they don't come in contact with
Foods maintain their texture and appearance, because microorganisms such
as bacteria mold and yeast cannot grow in a vacuum.
Freezer burn is eliminated, because foods no longer become dehydrated
from contact with cold, dry air.
Moist foods won't dry out, because there's no air to absorb the moisture
from the food.
Dry, solid foods, such as brown sugar, won't become hard, because they
don't come in contact with air and, therefore, can't absorb moisture from
Foods that are high in fats and oils won't become rancid, because there's
no oxygen coming in contact with the fats, which causes the rancid taste and
Insect infestation is eliminated, because insects require oxygen to
survive and hatch.
Meat and fish will marinade in minutes when vacuum packaged in canisters,
because as air is being removed from the canister, the pores of the mat or
fish open up and allow the marinade to penetrate.
Food bills are reduced because food lasts longer (so less spoiled food
will need to be thrown away), and because food can be purchased in
lower-priced bulk quantities and re-packaged at home into smaller portions.
And non-food items are protected from corrosion and moisture-damage. Like
your antique silverware, which won't tarnish when vacuum packaged. Or wool
sweaters, to keep bugs away, and to shrink them for minimal storage space.
Types of home vacuum packaging systems
Manually operated vacuum pumps.
These systems consist of a small manually-operated pump which can be used
to extract air from canisters and bottles only. They do not usually indicate
when a vacuum has been achieved.
Although they do not completely remove the air from the container, they
do help food last longer. Glass or glazed ceramic containers work best.
Bag sealers with a fan.
These systems utilize small rotary fans to extract some air out of
plastic bags before they are sealed. Some systems include polyethylene bags.
Others provide sheets of plastic from which bags of different lengths can be
made by "welding" the seams with a heated wire bag-sealing mechanism.
The fans don't have enough suction to create a vacuum. The amount of air
removed is comparable to using a straw to suck air out of the bag. The
plastic will shape itself loosely to the contours of the food in the bag,
but it will be obvious that air remains in the bag. The type of bag material
(polyethylene is best) and the strength of the seal will determine whether
oxygen is able to re-enter the bag.
Less-air is better than out-in-the-air. Remember, however, that plastic
does breathe, so storage life will be limited.
Electric pump systems.
These are the only storage systems that eliminate exposure to oxygen.
They are also the most expensive, of course.
They utilize electric-powered piston pumps to extract air from the
container, and seal with container to prevent air from re-entering. And,
ideally, they indicate when a vacuum has been achieved.
When food is vacuum packed in bags, the effect of the pump is highly
visible, because the bags will shape themselves tightly around the food. Not
so when vacuum packed in a jar, which is when a vacuum gauge is most helpful
and will keep the jar from imploding.
In order to maintain the vacuum, containers are constructed of special
materials which provide an oxygen barrier.
Vacuum packaging is not a substitute for
canning or dehydration
Vacuum packaged food will taste fresher and last longer than food stored
in conventional containers.
But because the food is not devoid of moisture or potentially lurking
pathogens, it is important to remember that vacuum packaging is not an
alternative to refrigeration.
Of course you don't need to refrigerate vacuum packaged cereal. But you
do have to refrigerate meat, dairy and other products that require it.
Shelf life of vacuum packaged foods
||Normal Shelf Life
||Vacuum Shelf Life
|Large cuts of meat: beef, poultry, lamb and pork
|Ground meat: beef, poultry, lamb and pork
|Berries: strawberries, raspberries, blackberries
|Berries: cranberries, huckleberries, blueberries
||Room temperature (periodically opening)
|Flour, sugar, rice
|Oils with no preservatives, like safflower, canola,
Above table adapted by Tilia Inc. from Dr. G.K.York, Dept. of
Food Science & Tech, U of California, Davis.